Synthesis, characterization, cytotoxic activities, and DNA-binding properties of the La(III) complex with Naringenin Schiff-base Original Research Article

A new Naringenin Schiff-base ligand (H3L) and its complex, [La(H2L)2(NO3)·3H2O], have been synthesized and characterized on the basis of elemental analyses, molar conductivities, mass spectra, 1H NMR, thermogravimetry/differential thermal analysis (TG–DTA), UV spectra, and IR spectra. Spectrometric titrations, ethidium bromide displacement experiments, and viscosity measurements indicate that the two compounds, especially the La(III) complex, strongly bind with calf-thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constants of the La(III) complex and ligand with DNA were 1.83 × 107 and 9.46 × 105 M−1, respectively. Comparative cytotoxic activities of the La(III) complex and ligand were also determined by MTT [3-(4,5-dimethyl-2-thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide] and SRB (sulforhodamine B) methods. The results showed that the La(III) complex had significant cytotoxic activity against the tested cells.